This invention relates to a novel aromatic polyester, aromatic polyester-amide and processes for producing the same.
The aromatic polyester and the aromatic polyester amide of the present invention show liquid crystallinity (optical anisotropy) at melting so that they exhibit excellent properties in moldability (fluidity), and have high modulus of elasticity, high strength, high heat resistance and also low water absorption. They are particularly excellent in soldering resistance so that they can be utilized as an electric or electronic material such as a precision component, a connector, an IC socket, an encapsulated material, etc., a molding, such as a part for automobile, etc., a film, a fiber, etc.
Also, when the processes of the present invention are employed, the aromatic polyester and the aromatic polyester-amide of the present invention can be prepared by conventional and usual apparatus for preparing polyesters, thereby improving productivity and reduced costs.
In recent years, in the fields of moldings of precision instrument parts, electric or electronic parts, or automobile parts, or film, fiber, etc., have seen an increased demand for engineering plastics excellent properties in terms of rigidity, heat resistance, chemical resistance, etc. As a polyester satisfying such demands in recent years, a liquid crystal polyester, for example, a copolyester showing melt anisotropy, obtained by polyethylene terephthalate and p-acetoxybenzoic acid ("Journal of Polymer Science Polymer Chemistry Edition ", vol. 14, p. 2043 (1976) and Japanese Patent Publication No. 18016/1981 ), etc. has attracted some attention. This liquid crystalline copolyester, obtained by polyethylene terephthalate and p-acetoxybenzoic acid, has excellent mechanical properties without blending a reinforcing material and, for example, it has been reported that it has 5-fold or more of modulus of elasticity, 4-fold or more of strength and 25-fold or more of impact strength as compared with polyethylene terephthalate.
However, this liquid crystalline copolyester does not have good heat resistance, and particularly, it has no soldering resistance so that it cannot be used for electronic parts, etc. Thus, it has disadvantages that limit its use considerably.
On the other hand, as an aromatic polyester containing a constitutional unit represented by ##STR1## various examples have hitherto been known. For example, there are described in British Polymer Journal, 154 (1980); Macromolecules, 16 (7), 1027 (1983); IUPAC Macromol. Symp. 28th, 200 (1982); U.S. Pat. Nos. 4,067,852 and No. 4,664,972; Japanese Patent Applications Laid-Open No. 156313/1987, No. 206017/1987, No. 39623/1987 and No. 48722/1987; etc.
These aromatic polyesters have disadvantages of lacking soldering resistance, or in those cases having soldering resistance, they sometimes cannot be prepared by conventional polyester producing apparatus (for example, the bulk method reacting in a vertical type polymerization reactor at 320.degree. C.).
For example, according to British Polymer Journal, 154 (1980) and U.S. Pat. No. 4,067,852, a polyester comprising ##STR2## has high melting point of 330.degree. C. or higher so that it cannot be prepared by the conventional apparatus for polyester, which is conventionally used at 320.degree. C. or lower. For this reason, this polyester is prepared with the use of a solvent or at a temperature as high as 335.degree. C. A polyester comprising ##STR3## has further high melting point (500.degree. C. or higher), so that production by the conventional apparatus for producing polyester is impossible.
Also, according to the description of Macromolecules, 16, 1027, (1983), a polyester comprising ##STR4## has been described in detail, but melting points thereof are as high as 320.degree. C. or higher in any composition ratio of these four components whereby they cannot be prepared by the conventional polymerizing apparatus which has been used at 320.degree. C. or lower.
In the above document, the melting point has been lowered by using ##STR5## in place of ##STR6## but in this case, while the melting point has remarkably been lowered, the polymer becomes amorphous so that soldering resistance at 260.degree. C. is lost.
Regarding a polyester comprising ##STR7## there are many reports, but in this case, it is clear that it cannot be prepared by the conventional and usual polyester-producing apparatus.
Further, as an aromatic polyester-amide containing a constitutional unit represented by ##STR8## there are descriptions in British Polymer Journal, vol. 13, No. 1, p. 5 (1981), Japanese Patent Applications Laid-Open No. 177021/1982 and No. 27391/1980, etc., but any one of which only uses, as a nitrogen-containing component, an aromatic diamine compound unit or an aromatic amino-oxy compound unit.
Regarding an aromatic polyester- amide containing an aminocarboxylic acid unit, there is a description in macromolecules, vol. 20, No. 4, p. 877 (1987), but this is high content in the aminocarboxylic acid unit as 50 equivalent % so that it can be considered to involve a problem in water absorption properties. Also, there is no description whether this aromatic polyester -amide has liquid crystallinity.
Regarding an aromatic polyester- amide containing an aminophenol unit, there are descriptions in British Polymer Journal, vol. 13, No. 1, p. 5 (1981), Japanese Patent Application Laid-Open No. 177021/1987 and No. 27391/1980, but any one of which has problems that they have high softening points, cannot be produced by the conventional polyester-producing apparatus, and also do not show any liquid crystallinity. Further, there is no description concerning soldering resistance. Moreover, in Japanese Patent Application Laid-Open no. 284221/1988, there is a description concerning an aromatic polyester amide using a starting material of m-orientation, and examples of polymerization at 320.degree. C. have been mentioned. However, each of which has a heat deflection temperature of 200.degree. C. or lower and thus, it would be clear that they do not have practical soldering resistance (260.degree. C. .10 sec).
The present inventors have investigated, in such circumstances, to provide an aromatic polyester and an aromatic polyester- amide which have high modulus of elasticity, high strength and low water absorption, are excellent in heat resistance, particularly in soldering resistance (240.degree. C., or 260.degree. C., 10 sec or more ) and yet excellent in fluidity and good in moldability, and which are suitable for engineering plastics, and to provide processes for producing these by using the conventional and usual polyester-producing apparatus (for example, a vertical type polymerization reactor used in the bulk method at a temperature of 320.degree. C. or below) with good efficiency. As the results, they have found that the aromatic polyester and the aromatic polyester-amide having the composition mentioned hereinbelow in detail have satisfied the above objectives, and based on this finding the present invention has been accomplished.